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Merge pull request #3343 from Blub/apparmor-mount-rule-generation

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apparmor: generate ro,bind,remount rule list
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Christian Brauner 2020-04-01 21:16:34 +02:00 committed by GitHub
commit 632dd634f9
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1 changed files with 110 additions and 14 deletions
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124
src/lxc/lsm/apparmor.c
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@ -132,6 +132,16 @@ static const char AA_PROFILE_BASE[] =
"# mount options=(rw,make-unbindable) -> **,\n"
"# mount options=(rw,make-runbindable) -> **,\n"
"\n"
"# Allow limited modification of mount propagation\n"
" mount options=(rw,make-slave) -> /,\n"
" mount options=(rw,make-rslave) -> /,\n"
" mount options=(rw,make-shared) -> /,\n"
" mount options=(rw,make-rshared) -> /,\n"
" mount options=(rw,make-private) -> /,\n"
" mount options=(rw,make-rprivate) -> /,\n"
" mount options=(rw,make-unbindable) -> /,\n"
" mount options=(rw,make-runbindable) -> /,\n"
"\n"
" # allow bind-mounts of anything except /proc, /sys and /dev\n"
" mount options=(rw,bind) /[^spd]*{,/**},\n"
" mount options=(rw,bind) /d[^e]*{,/**},\n"
@ -150,15 +160,18 @@ static const char AA_PROFILE_BASE[] =
" mount options=(rw,bind) /sy[^s]*{,/**},\n"
" mount options=(rw,bind) /sys?*{,/**},\n"
"\n"
" # allow various ro-bind-*re*-mounts\n"
" mount options=(ro,remount,bind),\n"
" mount options=(ro,remount,bind,nosuid),\n"
" mount options=(ro,remount,bind,noexec),\n"
" mount options=(ro,remount,bind,nodev),\n"
" mount options=(ro,remount,bind,nosuid,noexec),\n"
" mount options=(ro,remount,bind,noexec,nodev),\n"
" mount options=(ro,remount,bind,nodev,nosuid),\n"
" mount options=(ro,remount,bind,nosuid,noexec,nodev),\n"
" # Allow rbind-mounts of anything except /, /dev, /proc and /sys\n"
" mount options=(rw,rbind) /[^spd]*{,/**},\n"
" mount options=(rw,rbind) /d[^e]*{,/**},\n"
" mount options=(rw,rbind) /de[^v]*{,/**},\n"
" mount options=(rw,rbind) /dev?*{,/**},\n"
" mount options=(rw,rbind) /p[^r]*{,/**},\n"
" mount options=(rw,rbind) /pr[^o]*{,/**},\n"
" mount options=(rw,rbind) /pro[^c]*{,/**},\n"
" mount options=(rw,rbind) /proc?*{,/**},\n"
" mount options=(rw,rbind) /s[^y]*{,/**},\n"
" mount options=(rw,rbind) /sy[^s]*{,/**},\n"
" mount options=(rw,rbind) /sys?*{,/**},\n"
"\n"
" # allow moving mounts except for /proc, /sys and /dev\n"
" mount options=(rw,move) /[^spd]*{,/**},\n"
@ -324,12 +337,13 @@ static const char AA_PROFILE_NESTING_BASE[] =
"\n"
" mount fstype=proc -> /usr/lib/*/lxc/**,\n"
" mount fstype=sysfs -> /usr/lib/*/lxc/**,\n"
" mount options=(rw,bind),\n"
" mount options=(rw,rbind),\n"
" mount options=(rw,make-rshared),\n"
"\n"
/* FIXME: What's the state here on apparmor's side? */
" # there doesn't seem to be a way to ask for:\n"
" # Allow nested LXD\n"
" mount none -> /var/lib/lxd/shmounts/,\n"
" mount /var/lib/lxd/shmounts/ -> /var/lib/lxd/shmounts/,\n"
" mount options=bind /var/lib/lxd/shmounts/** -> /var/lib/lxd/**,\n"
"\n"
" # FIXME: There doesn't seem to be a way to ask for:\n"
" # mount options=(ro,nosuid,nodev,noexec,remount,bind),\n"
" # as we always get mount to $cdir/proc/sys with those flags denied\n"
" # So allow all mounts until that is straightened out:\n"
@ -631,6 +645,86 @@ static bool is_privileged(struct lxc_conf *conf)
return lxc_list_empty(&conf->id_map);
}
static const char* AA_ALL_DEST_PATH_LIST[] = {
" -> /[^spd]*{,/**},\n",
" -> /d[^e]*{,/**},\n",
" -> /de[^v]*{,/**},\n",
" -> /dev/.[^l]*{,/**},\n",
" -> /dev/.l[^x]*{,/**},\n",
" -> /dev/.lx[^c]*{,/**},\n",
" -> /dev/.lxc?*{,/**},\n",
" -> /dev/[^.]*{,/**},\n",
" -> /dev?*{,/**},\n",
" -> /p[^r]*{,/**},\n",
" -> /pr[^o]*{,/**},\n",
" -> /pro[^c]*{,/**},\n",
" -> /proc?*{,/**},\n",
" -> /s[^y]*{,/**},\n",
" -> /sy[^s]*{,/**},\n",
" -> /sys?*{,/**},\n",
NULL,
};
static const struct mntopt_t {
const char *opt;
size_t len;
} REMOUNT_OPTIONS[] = {
{ ",nodev", sizeof(",nodev")-1 },
{ ",nosuid", sizeof(",nosuid")-1 },
{ ",noexec", sizeof(",noexec")-1 },
};
static void append_remount_rule(char **profile, size_t *size, const char *rule)
{
size_t rule_len = strlen(rule);
for (const char **dest = AA_ALL_DEST_PATH_LIST; *dest; ++dest) {
must_append_sized(profile, size, rule, rule_len);
must_append_sized(profile, size, *dest, strlen(*dest));
}
}
static void append_all_remount_rules(char **profile, size_t *size)
{
/*
* That's 30, and we add at most:
* ",nodev,nosuid,noexec,strictatime -> /dev/.lx[^c]*{,/ **},\ n",
* which is anouther ~58, this s hould be enough:
*/
char buf[128] = " mount options=(ro,remount,bind";
const size_t buf_append_pos = strlen(buf);
const size_t opt_count = ARRAY_SIZE(REMOUNT_OPTIONS);
size_t opt_bits;
must_append_sized(profile, size,
"# allow various ro-bind-*re*mounts\n",
sizeof("# allow various ro-bind-*re*mounts\n")-1);
for (opt_bits = 0; opt_bits != 1 << opt_count; ++opt_bits) {
size_t at = buf_append_pos;
unsigned bit = 1;
size_t o;
for (o = 0; o != opt_count; ++o, bit <<= 1) {
if (opt_bits & bit) {
const struct mntopt_t *opt = &REMOUNT_OPTIONS[o];
memcpy(&buf[at], opt->opt, opt->len);
at += opt->len;
}
}
memcpy(&buf[at], ")", sizeof(")"));
append_remount_rule(profile, size, buf);
/* noatime and strictatime don't go together */
memcpy(&buf[at], ",noatime)", sizeof(",noatime)"));
append_remount_rule(profile, size, buf);
memcpy(&buf[at], ",strictatime)", sizeof(",strictatime)"));
append_remount_rule(profile, size, buf);
}
}
static char *get_apparmor_profile_content(struct lxc_conf *conf, const char *lxcpath)
{
char *profile, *profile_name_full;
@ -648,6 +742,8 @@ static char *get_apparmor_profile_content(struct lxc_conf *conf, const char *lxc
must_append_sized(&profile, &size, AA_PROFILE_BASE,
STRARRAYLEN(AA_PROFILE_BASE));
append_all_remount_rules(&profile, &size);
if (aa_supports_unix)
must_append_sized(&profile, &size, AA_PROFILE_UNIX_SOCKETS,
STRARRAYLEN(AA_PROFILE_UNIX_SOCKETS));